1. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to materials and devices for use in medical imaging applications.
2. Description of Related Art
Stereotactic surgery involves the use of a precision apparatus and guided placement of surgical instruments to enable the surgeon to target precisely a structure within a bodily organ, such as the brain. Stereotaxic surgery may involve accurate localization of targets within the brain, for example, to insert electrodes for treatment of various neurological diseases (thalamotomy, pallidotomy, or insertion of brain stimulators to treat Parkinson""s disease or tremor) or pain (particularly cancer pain), or to guide the surgeon to resect brain tumors with accuracy in order to optimize tumor removal and to minimize injury to surrounding brain tissue. Stereotactic radiosurgery or stereotactic radiotherapy uses similar localizing techniques to guide radiation to specifically confined areas within the brain.
A common stereotactic surgical technique includes a step of first identifying the target organ by imaging means such as a computerized axial tomography (CAT) scan using X-rays or a magnetic resonance imaging (MRI) scan. A stabilized insertion platform is affixed exteriorly to the body to hold a cannula or other locator device in fixed relation to the target organ. In the case of brain surgery a halo device is typically used as a stabilized insertion platform. The halo device may comprise any structure that is rigidly affixed to the cranium to hold a cannula or other device in fixed relation to the skull. A probe that is connected to the stabilized insertion platform is directed into an intra-cranial region of the cranium, based on predetermined coordinates derived from earlier diagnostic analysis for example. The predetermined coordinates may represent an approximation of a target location within the brain. Prior art analytical and medical instrumentation and procedures, which are suitable for stereotaxic surgery, are well known and for the sake of simplicity will not be detailed further herein.
Despite their widespread use, a certain margin of error in localization exists with prior-art stereotactic surgical procedures. This error may vary, for example, from 1 mm to 5 mm. Therefore, when precise localization is required, refinement of existing technology may be desired.
The present invention provides an apparatus and method for more accurately positioning instrumentation in an organ, such as a brain, of a patient. The apparatus is straightforward in design and construction and can be used with existing technology without requiring a substantial level of increased surgical skill.
In accordance with an aspect of the present invention, a marker assembly is formed of a carbon fiber composition to provide enhanced, high-definition imaging. The marker assembly includes a shaft sized and shaped to be inserted into an organ, wherein the shaft includes a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end. The distal end of the shaft is sized and shaped to be positioned near a target region within the organ, and the shaft includes a lumen extending through the shaft in a direction parallel to the longitudinal axis of the shaft. The lumen is constructed to accommodate a needle therethrough, so that the needle enters through the proximal end of the shaft, extends through the shaft, and exits through the distal end of the shaft. The marker assembly can also include other radiopaque or semi-radiopaque materials that provide higher definition imaging than titanium when implanted within the organ.